The sign you are referring to is known as the "Exemption from traffic ban according to § 40 paragraph 1 BImSchG (in conjunction with sign 270-1) - red, yellow, and green badge."

This sign indicates that vehicles that are equipped with specific environmental badges are exempt from certain traffic restrictions or bans, usually associated with emissions and air quality regulations. In Germany, vehicles are categorized based on their emissions, and these badges are color-coded—red, yellow, and green—to signify the level of pollution they produce.

- A red badge indicates that the vehicle has high emissions and is subject to more restrictions.
- A yellow badge signifies medium emissions, with some restrictions based on local regulations.
- A green badge represents low emissions, allowing the vehicle more access to restricted zones.

This sign typically appears in urban areas where environmental protection measures are enforced, and it lets drivers know that if their vehicle has the correct badge, they may enter or travel through zones that would otherwise have traffic bans in place for certain vehicles. Always ensure to check your vehicle's badge and local regulations to remain compliant while driving in restricted areas.

If you have any further questions about traffic rules or other signs, feel free to ask!